Sheet advance apparatus

ABSTRACT

Apparatus for intermittently advancing successive equivalent length portions of a generally continuous sheet through an upstream article forming station. A gear assembly intermediate drive means and a sheet advance roll includes a Geneva assembly which, in combination with a brake on the roll, controls its acceleration and deceleration to provide smooth sheet movement. The extent of sheet displacement may be quickly changed by means of a lever having a portion mounted exterior to the housing of the gear assembly which, when rotated, changes the center distance between a rotary crank in the input drive train and a pivot shaft of the Geneva assembly which receives power from the input drive train.

United States Patent [72] Inventors Bruce T. Jope South Glastonbury;Leonard J. Witkowski, Windsor Locks, both of Conn. [21] Appl. No.860,874 [22] Filed Sept. 25, 1969 [45] Patented Oct. 19, 1971 [73]Assignee Monsanto Company St. Louis, Mo.

[54] SHEET ADVANCE APPARATUS 5 Claims, 8 Drawing Figs.

[52] 11.8. CI 226/142, 226/145, 226/178 [51] Int. Cl B65h 17/22 [50]Field of Search 226/138, 139, 140,141, 142,137, 145

[56] References Cited UNITED STATES PATENTS 2,757,584 8/1956 Clemente226/141 X 3,517,872 6/1970 Chmela 226/141 X FOREIGN PATENTS 954,12512/1949 France Primary Examiner-Allen N. Knowles Attorneys-James C.Logomasini, Michael]. Murphy and Neal E. Willis ABSTRACT: Apparatus forintermittently advancing successive equivalent length portions of agenerally continuous sheet through an upstream article forming station.A gear assembly intermediate drive means and a sheet advance rollincludes 21 Geneva assembly which, in combination with a brake on theroll, controls its acceleration and deceleration to provide smooth sheetmovement. The extent of sheet displacement may be quickly changed bymeans of a lever having a portion mounted exterior to the housing of thegear assembly which, when rotated, changes the center distance between arotary crank in the input drive train and a pivot shaft of the Genevaassembly which receives power from the input drive train.

PATENTEDUCT 19 m1 SHEET 10F 3,

INVENT( )RS BRUCE T JOPE LEONARD J. WITKOWSKI W ATTORNEY UCTIQIBTI 3, '1PATENTED SHEET am 3 510 979 FIG. 3

W- iniill l i m INVEN'IY )RS BRUCE T. JOPE LEONARD J. WITKOWSKI ATTORNEYSHEET ADVANCE APPARATUS BACKGROUND OF THE'INVENTION This inventionrelates in general to improvements in equipment for forming articlesfrom sheet, and in particular to improvements in apparatus foradvancingthe sheet through an article forming press.

Several different types of forming areknown for simultaneously shapinglarge numbers of articles in a single cycle from portions of a generallycontinuous plastic sheet. One technique: is by pneumatic pressuredifferential formingv of container depressions in a large heated area.of the sheet against the; surfaces of mold cavities using peripheralsealing blades to. hold the pressure in each mold during forming,followed by a creasing of the web by the blades around the formedarticles at the seal while still in the press. This creasing is almostbut not entirely through the-web, in order that the articles may betransferred out of the forming station and thereafter easily peeled fromthe web along the creases by merely directing the web in a directiondifferent from that of the containers. The scrap sheet with thecontainers removed therefrom passes throughthe nip of a pair of opposingrolls whereupon it may be cut up or stored as desired. US. Pat. No. Re26,413 illustrates a machine operating on these principles. This type offorming is referred to as a type of trim in place thermoforming, asopposed to post trim thermoforming wherein a separate trimming press isrequired downstream of the forming operation to separate the containersfrom the sheet, or the cut in place technique wherein the articles areentirely severed from the sheet while in the forming press and then mustbe individually removed therefrom. From the standpoint of speed andeconomy, trim in place therrnoforming of the first mentioned variety ishighly desirable since the portion of the sheet or web between the moldcavities is used to transport the containers out of the forming presswhile the articles are still attached to theweb, thus facilitatingsubsequent removal by simple peeling.

The means used to advance the generally continuous sheet through theforming press of a trim in place installation is generally positioneddownstream of the station where the articles are disengaged from thesheet, and operates by pulling on the scrap sheet from which thearticles have been removed. Since the scrap sheet is integrallyconnected to the upstream sheet through the portions intermediate thesections where the articles are formed, this pulling in turn movesgenerally continuous upstream sheet portions into and out of the formingpress. Needless to say, the extent of sheet advance during a cycle ofthe equipment must be rather accurately controlled, since if it varieson the lowside, articles formed in the previous cycle may still haveportions left within the forming press which may be crushed when thepress closes for the next cycle, whereas if it varies on the high side,sheet utilization is decreased since the portion of the sheet betweenadjacent sets of articles from successive cycles is greater than need beand the amount of scrap is high. The sheet must also be advanced quicklyto minimize cycle time, yet movement must be smooth in the sense that itis without sudden stops and starts, since if the sheet is jerked it maycause stretching of heated portions and premature stripping of theeasily removable articles from the sheet, whereas a sudden stop willcause sheet buckling. Also, since the product configuration being formedduring a given run is usually only one of many possible varieties, it isnecessary to frequently change the amount of sheet advance for a cycleby changing or altering the parts of the sheet advance means toaccommodate a different size or shape of product to be made during thenext run. Obviously, it is desirable to be able to make these changesquickly and with a minimum of effort to minimize changeover costs.

Though the means used to advance the sheet in. the past has generallyperformed satisfactorily, it has. been deficient at one time or anotherin onev or moreof the above-mentioned areas. Thus mechanical, stopsmounted on a drive chain were used to delimit the stroke of a pneumaticpiston, to define the limits and change the extent of sheet advance.After extended periods, these would become loose and, sheet travel wouldvary. The speed of the piston stroke which determines the rate of sheetadvance could not be controlled throughout the extent of its travel andthis resulted in jerky sheet movement.

Now there has been developed a unique apparatus which provides rapid yetsmooth sheet advancement, high repeatability of sheet travel duringsuccessive cycles and easily variable sheet displacement.

Accordingly, it is a principleobject ofthis invention to provideanimproved-sheet advance apparatus component for use in an equipmentsystem for forming articles from sheet material.

Another object of this invention is to provide. an improved apparatusfor intermittently advancing,successiveequivalent length portions of agenerally continuous thennoplastic sheet through an upstream articleforming station wherein, sheet movement is rapid yet smooth in thesensethat it is free of abrupt starts and stops.

A further object of this invention is to; provide apparatus of theaforementioned variety which is versatilein the sense that it may bereadily adjusted to changethe-extent of sheet travel in a minimum amountof time.

An additional object of this invention is to provide apparatus of theaforementioned variety wherein. the rate of change of sheet velocityduring advancement is controlled over the full extent of the sheettravel.

A further object of this invention is to-provide apparatus of theaforementioned variety wherein the accuracy of sheet displacement ishigh and reproducible overextended periods of use.

Other objects of this invention will in part be obvious and will in partappear hereinafter.

SUMMARY OF THE INVENTION These and other objects are accomplished byproviding apparatus for intermittently advancing successive equivalentlength portions of a sheet through an upstream articleforming presscomprising, in combination, cylindrical sheet advance means including asheet drive roll withwhich a scrap portion of the sheet comes intoperipheral contact duringits advancing movement, drive means forintermittently rotating the sheet drive roll, a gear assemblyintermediate the sheet drive roll and the drive means for controllingthezamount of rotation and the speed of rotation of the sheet driverollthroughout the full extent of the sheet advance movement, a housing forthe gear assembly and means associated with the housing and the gearassembly to permit externally changing, the position of components ofthe gear assembly within. the housing to facilitate rapid adjustment ofthe amount of rotation of the sheet drive roll.

The gear assembly includes a Geneva assembly intermediate an input andan output gear train. The'Geneva assembly includes aninside-outsideGeneva-arm which is driven by a constant r.p.m. butchangeable crank-in theinput gear. tr'ain. A slider block pivotallyconnects the-crank to the arm such that the rotary motion of the crankisconverted to oscillatory motion of the arm. The armis fixedly mountedon a pivot shaft of the Geneva assembly which is connected into theoutput gear train to thereby transmit the oscillatory motion to thesheet drive roll which is coupled to the output gear train.

Means are provided to arrest the rotary motion of the sheet drive rollduring the latter part of the sheet advance cycle, which means includesa magnetic brake on'the-sheet drive roll which is energized by a switchactivated by the oscillating-armof the Geneva assembly at about themidpoint of the first half of its swing, so as to drive the sheetadvance roll through the deceleration latter portion of the swing of thearm of the Geneva assembly.

The means for externally changing the positionv of components of thegear assembly within the housing includes an adjusting lever pivotableabout the input shah of the gear assembly. The lever has a portionexternal to the housing through which an input force may be applied tochange the position of a stub shaft about which the crank rotates, whichin turn changes the center distance between the crank and the pivotshaft of the Geneva assembly which transmits the oscillatory motion tothe output gear train.

BRIEF DESCRIPTION OF THE DRAWINGS In describing the overall invention,reference will be made to the accompanying drawings in which:

FIG. 1 is a plan view of an equipment system for forming articles fromplastic sheet illustrating the sheet advance assembly of the inventionin dark lines and the remaining portions of the system in phantom;

FIG. 2 is partial, side elevational view of the equipment system of FIG.1;

FIG. 3 is a side elevational view of the sheet advance assembly of FIG.1;

FIG. 4 is a sectional view taken along 4-4 of FIG. 3;

FIG. 5 is a schematic, elevational view taken along 5-5 of FIG. 4;

FIG. 6 is a partial, sectional view taken along 6-6 of FIG. 4;

FIG. 7 is a schematic view, partly in section, of an optionalarrangement of parts of a portion of the sheet advance assembly; and

FIG. 8 is a sectional view taken along 8-8 of FIG. 4 with rotating partsshown in a slightly different position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to thedrawings, wherein identical numerals refer to identical parts, there isshown in FIGS. 1 and 2, a trim in place thermoforming assembly forsimultaneously forming a plurality of articles from thermoplastic sheetmaterial. This assembly includes apparatus generally indicated as 10 forintermittently advancing successive equivalent length portions of athermoplastic sheet S through a known, conventional upstream forrningstation shown in phantom in FIGS. 1 and 2. Further details of theoperation and construction of the known components of the thermoforrningassembly are set forth in U.S. Pat. No. Re 26,413, issued June 25, 1968,the content of which is herein incorporated by reference.

Apparatus 10 may be supported on a frame 12 which is fastened to themain frame of the forming press, and may in turn be supported on anystationary surface by one or more stanchions 14.

Apparatus 10 (FIG. 3) includes drive means, generally indicated as 16,which comprises variable speed DC motor 18 having a conventionalelectromagnetic clutch-brake assembly generally indicated as 20 includedwithin its housing. Gear reducer 22 is connected to the output shaft ofclutch-brake assembly 20 and in turn has drive sprocket 24 keyed on itsoutput shaft 26. Endless chain 28 is supported about the periphery ofdrive sprocket 24 and driven sprocket 30. Pedestal 21 supports drivemotor 18, electromagnetic clutchbrake 20 and gear reducer 22 on frame12. An adjustable slide 23 may be provided for setting the tension ofchain 28.

Cylindrical sheet advance means 32 (FIG. 1) are provided downstream ofthe area at which the containers are peeled out of the sheet. Thiscylindrical sheet advance means includes sheet drive roll 34 andimmediately adjacent driven roll 36 which together form a nip throughwhich the scrap sheet passes, for example into recovery container 38below the assembly. As is apparent from FIG. I, the scrap portion of thesheet after removal of the containers comes into peripheral contact withroll 34 during the advancement of the sheet as a result of the pressuredeveloped at the nip.

A gear assembly, 40 (FIG. 4) is provided intermediate sheet advancedrive roll 34 and drive means 16 for controlling the amount of rotationand the speed of rotation of drive roll 34 throughout the full extent ofthe sheet advance movement. A

housing or casing 42 split along its midpoint by means of flanges 44 isprovided for gear assembly 40. Gear assembly 40 comprises an input geartrain generally indicated as 46 (FIG. 8), an output gear train 48 (FIG.6) and a Geneva assembly 49 (FIG. 5) interconnecting input gear train 46with output gear train 48.

Input gear train 46 comprises unidirectional input rotary drive shaft 50on which driven sprocket 30 of drive means 16 is conventionally keyed totransmit power from drive means 16 to input gear train 46. Driving gear52 (FIG. 8) of input gear train 46 is mounted on drive shaft 50 on theopposite end from that on which sprocket 30 is located. Gear 52 mesheswith driven gear 54, which itself is pinned at 57 to crank 56. Crank 56comprises slider block arm 60 and slider block 62 which is pivotallymounted on slider block arm 60 by means of pivot pin 64. Crank 56 isrotatable about stub or crank shaft 58 by means of bearings 59.

Geneva assembly 49 (FIG. 4) comprises pivot shaft 66 rotatably mountedat either end by means of conventional bearings in the wall of the lowerportion of housing 42. Assembly 49 further comprises an inside-outsideGeneva arm 68 having a track 70 formed therein within which slider block62 reciprocates as generally indicated in FIG. 5. Track 70 has twohorizontal steel guides 72, one on either side of slider block 62 tokeep block 62 confined within track 70. Geneva assembly 49 furtherincludes hub 74 on which arm 68 is mounted. Hub 74 is pinned to pivotshaft 66 and comprises stiffening web 76 intermediate plate 78 and arm68.

Output gear train 48 (FIGS. 4 and 6) comprises output shaft 80 coupledat 82 to shaft 84 of sheet advance drive roll 34. Intermediate step-upgearing 86 on intermediate shaft 88 is rotatably mounted in conventionalbearings at one end in a wall of housing 42 and at its other end inpartition wall 90 within housing 42. Wall 90 also acts as a support forbearing mounted output shaft 80. Intermediate gearing 86 comprises firstgear 92 (FIG. 6) which intermeshes with segmental gear 94, which in turnis mounted on plate 78 of hub 74 of the Geneva assembly. Intermediategearing 86 further includes a second larger gear 98 for meshing withdriven gear 100 on output shaft 80. Stepdown gearing 86 serves to changethe rotary speed of output shaft 80 from that of pivot shaft 66 of theGeneva assembly.

A one-way clutch 102 is mounted between shaft 84 of sheet advance driveroll 34 and output shaft 80 of output gear train 48 and serves totransmit rotary power to shaft 84 of roll 34 when output shaft 80 isturning in one direction and to disengage output shaft 80 from shaft 84of sheet advance roll 34 when output shaft 80 rotates in the oppositedirection.

As an important feature of the invention, means associated with housing42 and gear assembly 40 are provided to permit externally changing theposition of components of gear assembly 40 within housing 42 tofacilitate rapid adjustment of the amount of rotation of sheet advancedrive roll 34. These means generally indicated as 104 (FIG. 4) comprisea crank arm 106 (FIG. 8) within the input gear train which is welded tohollow intermediate shaft portion 124, which in turn is pinned toadjusting flange 120, which as indicated in FIG. 8 is external tohousing 42. I-Iollow shaft portion 124 could be an integral extension offlange 120. Crank arm 106 is rotatably mounted in sleeve bearing 108about input shaft 50, whereas bearings 59 permit crank 56 to rotateabout crank or stub shaft 58 at a constant r.p.m. via gears 52 and 54.During operation of the apparatus, crank arm 106 itself remainsstationary. Gear 52 is pinned at 53 to an enlargement 55 on the innerend of input shaft 50. To change the center distance 4' (FIG. 5) betweenpivot shaft 66 of Geneva assembly 49 and crankshaft 58, crank arm 106 ismerely rotated on bearing 108, and since crankshaft 58 is press fittedinto a bore in arm 106, such rotation will result in a movement of shaft58 to either the right or the left (FIG. 5) depending on the directionof rotation of crank arm 106. End cap portion 107 and pin 109 insurethat shaft 58 remains axially fixed in the bore of arm 106. Ann 106 isrotated externally of housing 42 by means of rod 118 (FIG. 5) pivoted at128 to flange 120. Slots 122 in flange 120 define the limits of rotationof flange 120 and therefore the extent of adjustment. Bolts 126 areprovided for securing adjusting flange 128 to the upper half of housing42 after movement of adjusting flange 120. Rod 118 has a threaded lowerportion 130 extending through a threaded hole in nut 128. Clevis 132 ispinned to housing 42 above flange 120 and surrounds collar 134, which inturn is pinned to rod 1 18 within clevis 132. Thus when rod 1 18 ismanually rotated in a plane perpendicular to the axis of adjustableflange 120, rod 118 moves through the threaded hole in nut 128 so as tocause flange 128 to rotate in one direction while collar 132, pinned onrod 118 abuts against inner surfaces of the clevis and remainsstationary relative to housing 42. A dial 136, which may be calibratedin terms of sheet displacement and/or the size of the articles beingformed, is mounted on casing 42 adjacent adjusting flange 120. Pointer138 on adjusting flange 128 is intermediate dial 136 and flange 128.Thus, flange 120 hollow intermediate portion 124 and crank arm 106 serveas an adjusting lever which is pivotable about input shaft 50. Flange120 serves as a portion of the lever which is external to housing 42 andpivotally mounted rod 118 serves as the means by which an input forcemay be applied to the lever to change the position of stub shaft 58 withrespect to pivot shaft 66 of the Geneva assembly.

Means are also provided to arrest the rotary motion of sheet advanceroll 34 during the latter part of the sheet advance cycle. These meansinclude lower cam 140 (P10. 5) mounted by means of cam support 144 onshaft 66 of the Geneva assembly. Lower cam 140 coacts with follower 142which in turn is conventionally rotatably mounted on the end of a shortarm associated with electrical limit switch 146. Limit switch 146 ismounted on plate 152 which in turn is secured to housing 42. Magneticbrake 154 (FIG. 1) is coupled to shaft 84 of advance roll 34 on theopposite side from that connected to output shaft 80 of output geartrain 48. Magnetic brake 154 is of conventional design and basicallycomprises a plate splined to shaft 84 perpendicular to its axis andwhich rotates with shaft 84. An electromagnet is fixedly mounted on theframe of the apparatus spaced a short distance from and in a planeparallel with that of the plate. On electrically energizing the magnetby means of lower limit switch 146, the magnetic force applied againstthe plate moves the plate toward the magnet a distance on the order ofone-sixteenth inch. When this force is applied, the plate acts as a dragon shaft 84 on which the plate is mounted. Suitable conventionalelectric wiring is utilized to interconnect lower limit switch 146 withmagnetic brake 154.

Means are also provided to operate electromagnetic clutchbrake 20 ofdrive means 16 at a preselected time in the cycle. These means includeupper cam 143 which is adjustably mounted on cam support 144 by means ofbolt 156 movable in slot 158. Fine adjustment of the position of cam 143is achievable by means of bolt 1168. Cam 143 coacts with follower 158which is rotatably mounted on an arm associated with upper limit switch148 secured on plate 152 in the same manner as switch 146. Conventionalelectrical control wiring interconnects switch 148 with electromagneticclutch-brake 20.

ln operation, as the upper platen 162 of the forming press (FIG. 2)starts its upward movement on completion of a forming cycle, a limitswitch (not shown) which is adjustably mounted on the forming press isenergized to activate electromagnetic clutch-brake 20 so as to disengagethe brake portion thereof and to engage the clutch portion thereof. Thislimit switch is positioned such that it is energized by the upper platenonly when the latter has cleared the uppermost portion of the formedarticles which are then within the press. Otherwise if the sheet were tostart to move prior to this time, the articles could catch on thetooling and be prematurely stripped from the sheet.

Thus, with the clutch engaged, power is transmitted in one directionfrom continuously rotating variable speed motor 18 to input shaft 50 ofthe input gear train of the gear assembly 40, and thence through gears52 and 54 to the constant r.p.m. crank 56. During this time, of course,crank arm 106 is stationary. The rotary motion of crank 56 is convertedto longitudinal motion by means of slider block 62 pivotally mounted onslider block arm 60 and confined within track 70 of inside-outsideGeneva arm 68. Thus slider block 62 will move to the right (FIG. 5) soas to cause arm 68 of the Geneva assembly to move angularly upwardlythrough a total angle of about 45. This upward movement of arm 68 causespivot shaft 66 to rotate in a counterclockwise direction, and thisrotary motion is transmitted to the output gear train by means ofsegmental gear 94 which is mounted on hub 74 so as to cause shaft andthus shaft 84 of sheet advance roll 34 to rotate in one direction. Thisrotation causes the scrap portion of sheet 8 from which the articleshave been removed to feed into the nip of rolls 34 and 36 and thus topull an upstream portion of the sheet into the forming press. Duringthis portion of the sheet advance cycle the linear speed of advancementof the sheet is controlled by the relation of crank 56 to Geneva arm 68and the rotary speed of the output shaft of variable speed motor 18.Thus, to change the rate of advance of the sheet involves merelychanging the output speed of conventional variable speed motor 18. Whenarm 68 is one half way through its upward stroke, which positioncorresponds to the point of maximum arm velocity and the end of theaccelerating portion of the cycle, cam mounted on pivot shaft 66 andfollower 142 energizes lower limit switch 146 so as to activate magneticbrake 154 in order to apply a drag force on shaft 84 of sheet advanceroll 34. This drag force resists and is less than the power beingtransmitted thereto by the drive means. Thus roll 34 is positivelylinked to arm 68 and decelerated during the final portion of the upwardswing of arm 68, so as to drive roll 34 during this portion of theadvance. Otherwise roll 34 would freely rotate to a stop in a variablemanner under the influence of its own inertia and at its own pace. Limitswitch 146 may also be utilized to activate the means for loweringplaten 162, so that the relatively large platen may start downwardly tocommence the next cycle before the sheet has completed its movement tominimize cycle time. An electrical timer may be utilized in thecircuitry to permit an operator to synchronize the movement of theplaten with that of the sheet.

After arm 68 has reached the upper limit of its cyclic swing (shown inphantom in FIG. 5) further rotary motion of crank 56 in the samedirection causes confined slider block 62 to reverse its direction intrack 70 and proceed downward in the opposite direction to move intoposition for. the start of the next cycle. This reverse movement causespivot shaft 66 to rotate similarly in the opposite direction from thatin response to the upward stroke of arm 68, which in turn causes shaft80 of the output gear train and shaft 84 of advance roll 34 to likewisereverse rotation. However, one way clutch 102 isolates this reversemotion from shaft 84 of the sheet advance roll 34. Thus, since magneticbrake 154 is still energized, when arm 68 starts its downward stroke,the drag exerted by the brake in combination with the isolation providedby one way clutch 102, terminates the rotary motion of shaft 84 andtherefore the advance movement of sheet S. When arm 68 is close to thelower limit of its downward stroke defined by a horizontal position, cam143 in cooperation with follower energizes upper limit switch 148 whichin turn electrically causes the brake portion of electromagneticclutch-brake 20 to engage and the clutch portion to disengage so as toisolate the system from continuously operating drive motor 18 and thuscomplete one portion of the sheet advance cycle. Thus, the geometry ofthe gear assembly in combination with the one way clutch and themagnetic brake determine the accuracy of sheet displacement and not theposition of upper cam 143, since if the movement of arm 68 is terminatedat any point along its downward stroke the extent of advance of the nextcycle will be the same because power is transmitted to roll 34 as aresult of one way clutch 102 only during upward movement of arm 68. Tominimize overall cycle time, however, cam 143 is set to deactivate thesystem just before arm 68 reaches a true horizontal position. Thereuponupper platen 162 moves downwardly to commence formation of the nextseries of articles if it has not already started to do so during thelatter portion of the sheet advance as previously described. Duringforming, magnetic brake 154 remains energized so as to positivelyprevent sheet advance roll 34 from moving even slightly, which of coursewould be undesirable with respect to the forming operation. Brake 154,however, is deenergized by the limit switch which determines the startof the cycle so as to permit the sheet advance roll to be drivenunimpaired during the acceleration portion of the advance cycle. Brake154 in combination with the switches which energize and deenergize itthus provides positioning accuracy in the system without sacrifice inindexing speed since it is utilized only during the deceleration portionof the cycle. After the articles are formed the upper platen 162 startsto move upwardly to start the next sheet advance cycle.

Auxiliary features of the invention may include an additional limitswitch mounted on the outside of housing 42 and activated by lower cam140 to detect that the sheet has completed its forward advance. Thislimit switch would prevent upper platen 162 from completing its downwardstroke until the sheet has stopped its advance movement, or in otherwords would not allow platen 162 to complete its downward stroke unlessarm 68 of the Geneva assembly has reached the upper extremity of itsstroke. This feature avoids forming on a moving sheet.

Gear assembly 40 must be in a stationary condition when it is desired tochange the extent of sheet advance. Bolts 126 are merely loosened androd 118 pivoted one way or the other to change the center distancebetween crankshaft 58 about which crank 56 rotates and pivot shaft 66 ofthe Geneva assembly. This in essence changes the starting position ofslider block 62 in track 70 of arm 68 and therefore alters the extent ofthe angular rotation of arm 68, which in turn accordingly alters theamount of rotation transmitted'to shaft 84 of sheet advance roll 34. Thenew position is fixed by again securing bolts 126 to housing 42.

An alternate embodiment of the invention is illustrated in FIG. 7wherein pivotally connected arm 164 of the Geneva assembly reciprocatesthrough slide 172 having bushings 168 therein, and a hollow portion 170of pivot shaft 166 in response to the rotary motion imparted throughcrank arm 60 and gear 54, the latter being constructed similarly to thatshown in the preferred embodiment.

The above description and particularly the drawings are set forth forpurposes of illustration only and are not to be taken in a limited lsense.

The apparatus of the present invention is applicable to transfer cyclicpower to an output shaft which preferably is on a sheet advance roll inan assembly wherein movement of the sheet across a peripheral portion ofthe roll is smooth and variable. Since the sheet being advanced by theroll contacts a rather large surface area of the advance roll, it isespecially effective in applications where large articles have beenpreviously formed in and removed from the sheet. The constant angularvelocity of the rotating crank in the input gear train of the system isconverted via the Geneva assembly to a gradually increasing velocity ofthe sheet advance roll, then a relatively constant portion followed by agradual decrease which is approximately equivalent to that of theincrease Although the invention has been described with reference topreferred embodiments, it will be apparent to those skilled in the artthat the invention is not limited to the embodiments specificallyillustrated in the drawings. Those skilled in the art with the benefitof this invention, may readily envision additions, deletions,substitutions and modifications which would be consistent with orequivalent to the form of the invention herein described.

We claim:

1. Apparatus for intermittently advancing successive equivalent lengthportions of a sheet comprising in combinaa. cylindrical sheet advancemeans including a sheet drive roll with which the sheet comes intoperipheral contact during its advancing movement;

b. drive means for intermittently rotating the drive roll;

0. a gear assembly intermediate the drive roll and the drive means forcontrolling the amount of rotation of the drive roll, said gear assemblyincluding an input gear train, an output gear train and a Genevaassembly interconnecting said input gear train with the output geartrain;

d. a housing for the gear assembly;

e. means associated with the housing and the gear assembly to permitexternally changing the position of components of the gear assemblywithin the housing to facilitate rapid adjustment of the amount ofrotation of the drive roll; and

f. means for controlling the rotary speed of the drive roll throughoutthe full extent of the sheet advance movement.

2. The apparatus of claim 1 wherein the means to permit changing theposition of internal components of the gear assembly includes:

a. a crank arm in the input gear train to permit changing the positionof the output axis of the input gear train with respect to a pivot axisof the Geneva assembly;

b. an adjusting flange secured to and coaxial with said crank arm, saidflange having a portion external to said housing, said external portionhaving slots formed therein which define the limits of adjustment; and

0. means for rotating said flange when the drive means is disengaged sothat as the flange is rotated the crank arm is rotated to change therelative position of the output axis of the input gear train withrespect to the Geneva assembly.

3. The apparatus of claim 1 including means containing a magnetic brakefor arresting the rotary motion of the drive roll during the latter partof the sheet advance cycle.

4. The apparatus of claim 1 including a one-way clutch between the driveroll and the output shaft of the output gear train to transmit rotarypower to the advance roll when the output shaft of the output gear trainis turned in one direction and to disengage the output shaft from theadvance roll when the output shaft rotates in the opposite direction.

5. The apparatus of claim 1 wherein the drive means includes:

a. a variable speed drive motor;

b. power transmitting means between an input shaft of the input geartrain and the output shaft of the drive motor; and

c. an electromagnetic clutch-brake assembly between the powertransmitting means and the drive motor.

1. Apparatus for intermittently advancing successive equivalent lengthportions of a sheet comprising in combination: a. cylindrical sheetadvance means including a sheet drive roll with which the sheet comesinto peripheral contact during its advancing movement; b. drive meansfor intermittently rotating the drive roll; c. a gear assemblyintermediate the drive roll and the drive means for controlling theamount of rotation of the drive roll, said gear assembly including aninput gear train, an output gear train and a Geneva assemblyinterconnecting said input gear train with the output gear train; d. ahousing for the gear assembly; e. means associated with the housing andthe gear assembly to permit externally changing the position ofcomponents of the gear assembly within the housing to facilitate rapidadjustment of the amount of rotation of the drive roll; and f. means forcontrolling the rotary speed of the drive roll throughout the fullextent of the sheet advance movement.
 2. The apparatus of claim 1wherein the means to permit changing the position of internal componentsof the gear assembly includes: a. a crank arm in the input gear train topermit changing the position of the output axis of the input gear trainwith respect to a pivot axis of the Geneva assembly; b. an adjustingflange secured to and coaxial with said crank arm, said flange having aportion external to said housing, said external portion having slotsformed therein which define the limits of adjustment; and c. means forrotating said flange when the drive means is disengaged so that as theflange is rotated the crank arm is rotated to change the relativeposition of The output axis of the input gear train with respect to theGeneva assembly.
 3. The apparatus of claim 1 including means containinga magnetic brake for arresting the rotary motion of the drive rollduring the latter part of the sheet advance cycle.
 4. The apparatus ofclaim 1 including a one-way clutch between the drive roll and the outputshaft of the output gear train to transmit rotary power to the advanceroll when the output shaft of the output gear train is turned in onedirection and to disengage the output shaft from the advance roll whenthe output shaft rotates in the opposite direction.
 5. The apparatus ofclaim 1 wherein the drive means includes: a. a variable speed drivemotor; b. power transmitting means between an input shaft of the inputgear train and the output shaft of the drive motor; and c. anelectromagnetic clutch-brake assembly between the power transmittingmeans and the drive motor.